When motorists are pulled over on suspicion of drinking and driving, law enforcement officers may ask them to take a breath test. Roadside breath test devices are used to measure a driver’s blood alcohol content level and determine whether it is over the legal limit of 0.08. The problem stems from the fact that many roadside breath test devices yield inaccurate results when compared to the blood alcohol level readings obtained from an actual blood sample. According to the State University of New York at Potsdam, breath test results obtained from a roadside device may vary by at least 15 percent from the readings of an actual blood test. Furthermore, at least one in four people tested will have inflated breath test readings. This could lead to a wrongful DUI arrest and potentially false conviction.

There are several factors that contribute to the inaccurate readings obtained through a breath test device. Some of the following can influence readings and cause them to be higher than normal:

  •          The relative humidity and temperature of the air
  •          Cigarette smoke, gas fumes and pollution
  •          Electrical interference from cellphones or officers’ radios
  •          Residual food, drink, blood or vomit in a person’s mouth

Breath test devices must also be calibrated regularly and set to read in the temperature and humidity of the area in which they are being used. If law enforcement officers fail to use the device properly, it could lead to inaccurate results as well. The most accurate way of obtaining a BAC is to take a blood test.